Department of Rheumatology and Immunology, Second Xiangya Hospital, Central South University, Changsha 410011.
Department of Rheumatology and Immunology, People's Hospital of Liuyang, Changsha 410399, China.
Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2022 Apr 28;47(4):453-461. doi: 10.11817/j.issn.1672-7347.2022.210444.
Rheumatoid arthritis (RA) is a chronic autoimmune disease. MicroRNA has been shown to play an important role in RA. MicroRNA-124a (miR-124a) has anti-proliferative and anti-inflammatory effects in RA fibroblast synovial cells. This study aims to explore the effects of miR-124a overexpression on arthritis in collagen-induced arthritis (CIA) mice and the underlying mechanisms.
Bovine type II collagen and complete Ferris adjuvant were used to induce CIA model from DBA/1 mice. Twenty-eight days after initial immunization (D28), CIA mice were randomly divided into a model group, a miR-124a treatment group, and a negative control (NC) group. Physiological saline, miR-124a agomir, and miR-124a agomir NC were injected into the skin at the tail root of mice every 3 days for 4 times, respectively. The degree of joint swelling and arthritis index of mice were recorded accordingly. Sixty-three days after initial immunization (D63), the mice were sacrificed to obtain the synovial tissue of ankle joint. HE staining was used to observe the proliferation of synovial cell, infiltration of inflammatory cell, pannus, and bone erosion of synovial tissues; TUNEL staining was used to detect cell apoptosis; qRT-PCR was used to detect the mRNA expression of , phosphatidylinositol-3-kinase catalytic subunit alpha () and its downstream genes and . Immunohistochemistry was used to detect the protein expression of PIK3CA, Bcl-2, and Bax protein in synovial tissues of each group.
Different degrees of swelling presented in the paws of DBA/1 mice at D28, which indicated the CIA model was constructed successfully. Forty-eight days after initial immunization (D48), the paws of mice in the miR-124a treatment group were only slightly red and swollen, while the paws of mice in the model group and the NC group were obviously red and swollen. The arthritis index of mice in the miR-124a treatment group were decreased significantly compared to the NC group at D51, D53, D59, and D62 (51, 53, 59, 62 days after initial immunization) (all <0.05). Sixty-three days after initial immunization (D63), HE staining indicated that the scores of synovial cell proliferation, inflammatory cell infiltration, synovial pannus, and bone erosion were significantly reduced in the miR-124a treatment group (<0.05 or <0.01), while cell apoptosis was increased in the miR-124a treatment group compared with the model group and NC group (<0.01 or <0.001). Besides, the expression of miR-124a and Bax in the synovial tissue in miR-124a treatment group was significantly higher than those in the model group and NC group (<0.01 or <0.001), while the expressions of PIK3CA and Bcl-2 were decreased (<0.05 or <0.01 or <0.001), and the ratio of Bcl-2 to Bax was significantly decreased (<0.01 or <0.001).
Overexpression of miR-124a can reduce arthritis in CIA mice bacause it could promote synovial cell apoptosis and inhibit synovial cell proliferation via targeting PIK3CA and regulating its downstream pathways.
类风湿关节炎（RA）是一种慢性自身免疫性疾病。已有研究表明 microRNA 在 RA 中发挥重要作用。microRNA-124a（miR-124a）在 RA 成纤维样滑膜细胞中具有抗增殖和抗炎作用。本研究旨在探讨 miR-124a 过表达对胶原诱导性关节炎（CIA）小鼠关节炎的影响及其机制。
用牛Ⅱ型胶原和完全弗氏佐剂从 DBA/1 小鼠中诱导 CIA 模型。初次免疫后 28 天（D28），将 CIA 小鼠随机分为模型组、miR-124a 处理组和阴性对照（NC）组。分别于第 3 天在小鼠尾根部皮内注射生理盐水、miR-124a 激动剂和 miR-124a 激动剂 NC，共 4 次。根据关节肿胀程度和关节炎指数记录小鼠的情况。初次免疫后 63 天（D63）处死小鼠，获取踝关节滑膜组织。HE 染色观察滑膜细胞增生、炎症细胞浸润、滑膜绒毛和骨侵蚀；TUNEL 染色检测细胞凋亡；qRT-PCR 检测 、磷脂酰肌醇-3-激酶催化亚基α（）及其下游基因 和 的 mRNA 表达。免疫组化检测各组滑膜组织中 PIK3CA、Bcl-2 和 Bax 蛋白的表达。
初次免疫后 28 天（D28），DBA/1 小鼠的爪子出现不同程度的肿胀，表明 CIA 模型构建成功。初次免疫后 48 天（D48），miR-124a 处理组小鼠的爪子仅轻度红肿，而模型组和 NC 组小鼠的爪子明显红肿。初次免疫后 51、53、59、62 天（D51、D53、D59、D62），miR-124a 处理组小鼠的关节炎指数明显低于 NC 组（均<0.05）。初次免疫后 63 天（D63），HE 染色结果表明，miR-124a 处理组滑膜细胞增殖、炎症细胞浸润、滑膜绒毛和骨侵蚀评分明显降低（均<0.05 或 <0.01），细胞凋亡增加（均<0.01 或 <0.001）。此外，与模型组和 NC 组相比，miR-124a 处理组滑膜组织中 miR-124a 和 Bax 的表达明显升高（均<0.01 或 <0.001），而 PIK3CA 和 Bcl-2 的表达降低（均<0.05 或 <0.01 或 <0.001），Bcl-2 与 Bax 的比值明显降低（均<0.01 或 <0.001）。
miR-124a 的过表达可以减轻 CIA 小鼠的关节炎，因为它可以通过靶向 PIK3CA 并调节其下游通路促进滑膜细胞凋亡和抑制滑膜细胞增殖。
